Two or three weeks ahead is perfect. It makes it possible to be responsive to audience reaction in a timely manner and it won't take forever for writing changes to be felt. The only down side to Higley's firing is that we have to endure her garbage for so damn long because of how far ahead they are. And if the new writers want to change things so drastically that they have to go back and reshoot stuff that was taped way too far ahead, it'll end up costing them money. Money well spent, but money nonetheless.